Current management of secondary hyperparathyroidism: a multicenter observational study (COSMOS)

STUDY AIMS

To survey bone mineral disturbances in the hemodialysis (HD) population in Europe and current clinical practice in Europe for the prevention, diagnosis and treatment of secondary hyperparathyroidism (SHPT) in HD patients.

PRIMARY OBJECTIVES

First, to estimate the prevalence of Kidney Disease Outcomes Quality Initiative (K/DOQI) guideline achievement in a representative sample of European hemodialysis subjects. As part of this objective, we will investigate the prevalence of achievement by type of dialysis, type of center and time on dialysis (less than or greater than 1 year). Among new dialysis subjects (less than 1 year), we will evaluate prevalence of K/DOQI target achievement until the end of the study. The study will run for 3 years. Second, to estimate the association of bone mineral markers (parathyroid hormone [PTH], calcium [Ca], serum phosphorus [P] and calcium phosphate product [CaxP]) classified by achievement of K/DOQI targets with mortality and overall cardiovascular hospitalization. Third, to characterize the longitudinal changes in bone mineral markers. As part of this objective, we will describe the patterns and predictors of bone mineral markers and achievement, with K/DOQI targets, using repeated measurements on individuals over time.

SECONDARY OBJECTIVES

First, To estimate the association of bone mineral markers (PTH, Ca, P and CaxP) classified by achievement of K/DOQI targets with specific cardiovascular outcomes, parathyroidectomy, manifest bone disease (including incidence of symptomatic bone fractures), hospitalizations and vascular access. Second, to evaluate the additional value of albumin and hemoglobin levels in conjunction with bone mineral markers in the prediction of mortality and clinical events.

Measuring disease occurrence

Different measures may be used to describe how often disease (or another health event) occurs in a population. Incidence expresses the development of new cases and is mostly used against the background of prevention, to assess disease etiology or to determine the risk factors of disease. Depending on the specific study question, incidence may be reported as risk or as incidence rate. This paper discusses that it is preferable to use incidence rate in case of a dynamic population or in cases where the observation period is sufficiently long for competing risks or loss to follow-up to play a significant role. Prevalence is the number of existing cases, which is affected by both the number of incident cases and the length of disease time. It reflects the burden of disease on a population that may, among others, be measured in terms of costs or morbidity. Knowledge about this burden can be used for the planning of health-care facilities. This paper discusses the different measures of disease occurrence using a number of examples taken from the nephrology literature.

Prognostic associations of serum calcium, phosphate and calcium phosphate concentration product with outcomes in kidney transplant recipients

Disturbances in calcium and phosphate metabolism have been linked to increased mortality in hemodialysis patients, but not in kidney transplant recipients (KTR). We enrolled 733 KTR from the Vienna General Hospital into this study. Detailed demographic, clinical, laboratory, and transplant-related information was collected at baseline. We used the Austrian Dialysis and Transplantation Registry for follow-up. Using multivariate proportional hazard regression, we examined the independent associations between serum calcium, serum phosphate, and calcium phosphate (CaPO(4)) product with the outcomes of death from any cause and kidney allograft loss. Over a median follow-up of >6 years, 154 patients died and 259 kidney allografts were lost. Associations with serum calcium, phosphate concentrations, and CaPO(4) product concentrations were found for allograft loss, but not for patient mortality. Patients in the highest quintile of phosphate concentration and CaPO(4) product had an increased risk for allograft loss compared with patients in the lowest quintile of these parameters (hazards ratio, HR = 2.15; 95% confidence interval, CI: 1.36-3.40 and HR = 1.72; 95% CI: 1.10-2.71, respectively). High calcium levels were associated with a reduced risk for allograft loss. Results were even more pronounced for death-censored allograft loss. High concentrations of serum phosphate and CaPO(4) product were associated with an increased risk for allograft loss in these KTR, whereas high serum calcium concentrations seemed to lower the risk.

A J-shaped association between high-sensitivity C-reactive protein and mortality in kidney transplant recipients

In kidney transplant recipients (KTR), C-reactive protein (CRP) has been shown to be associated with increased mortality, but data on this association within the high-sensitivity (hs) range of CRP (<5 mg/l) are lacking. We prospectively studied 710 prevalent and stable KTR over >6 years. We thawed frozen plasma and measured baseline hs-CRP using an ultrasensitive assay. Detailed clinical and demographic baseline characteristics were available for study. We stratified patients by quartile of hs-CRP within the hs range (<5 mg/l), and also included KTRs whose hs-CRP was above the hs range (>5-10 and >10 mg/l). We used multivariate proportional hazards models to test for independent associations. After careful multivariate adjustment, we found a J-shaped association between hs-CRP and mortality. Compared with KTR whose hs-CRP was in the second lowest quartile of hs-CRP (0.06-1.26 mg/l), patients in the lowest quartile (<0.06 mg/l) had more than twice their mortality risk (HR = 2.07; 95% CI: 1.05-4.07), as did patients whose hs-CRP was > or =2.44 mg/l (all HRs >2.27). No association was found between hs-CRP and death-censored allograft loss. In contrast to the general population, the association between hs-CRP and mortality in KTRs is not linear, but J-shaped, suggesting that KTRs with very low hs-CRP may also be at increased risk of death.

A J-shaped association between high-sensitivity C-reactive protein and mortality in kidney transplant recipients

In kidney transplant recipients (KTR), C-reactive protein (CRP) has been shown to be associated with increased mortality, but data on this association within the high-sensitivity (hs) range of CRP (<5 mg/l) are lacking. We prospectively studied 710 prevalent and stable KTR over >6 years. We thawed frozen plasma and measured baseline hs-CRP using an ultrasensitive assay. Detailed clinical and demographic baseline characteristics were available for study. We stratified patients by quartile of hs-CRP within the hs range (<5 mg/l), and also included KTRs whose hs-CRP was above the hs range (>5-10 and >10 mg/l). We used multivariate proportional hazards models to test for independent associations. After careful multivariate adjustment, we found a J-shaped association between hs-CRP and mortality. Compared with KTR whose hs-CRP was in the second lowest quartile of hs-CRP (0.06-1.26 mg/l), patients in the lowest quartile (<0.06 mg/l) had more than twice their mortality risk (HR = 2.07; 95% CI: 1.05-4.07), as did patients whose hs-CRP was > or =2.44 mg/l (all HRs >2.27). No association was found between hs-CRP and death-censored allograft loss. In contrast to the general population, the association between hs-CRP and mortality in KTRs is not linear, but J-shaped, suggesting that KTRs with very low hs-CRP may also be at increased risk of death.

Age and sex are sufficient for predicting fractures occurring within 1 year of hemodialysis treatment

BACKGROUND

The incidence of fractures averages 20 per 1000 hemodialysis patient years at risk. This study sought to design and evaluate the utility of a simple prediction rule for fractures in dialysis patients using only standard demographical and biochemical information.

METHODS

1777 prevalent hemodialysis patients of the Austrian dialysis and transplant database who had an evaluation of fractures in 2004 and 2005 were included into analysis. Validation of the prediction rule model by a test set was performed using three different resampling techniques, the split sample approach, a 100-fold cross validation and a 100x bootstrap. Calibration of the model was performed visually by comparing the observed to the expected number of outcomes in each category and by calculating the Hosmer and Lemeshow goodness-of-fit statistic.

RESULTS

A multivariable logistic regression model built on clinical expertise yielded a discrimination of c=0.73 (AUC of ROC). Further reduction of the covariables to age and sex as the only predictive variables did not result in loss of discrimination (c=0.71) and at the same time provided adequate calibration (p=0.69). The probability of fractures (PF) occurring within the next year of hemodialysis can be calculated from our prediction model as, PF=e(-6.25+0.4*age(in decades)-0.93(if male))/1+e(-6.25+0.4*age(in decades)-0.93(if male)), e.g., a 70-year-old male would have a fracture probability of 0.01 or 1%, a female 3%. The optimism derived by all resampling techniques was between 1% and 2% suggesting adequate generalizability of the prediction rule.

CONCLUSION

A sufficient and parsimonious prediction rule for fractures in hemodialysis patients consists of the independent variables age and sex.

Present status at the Vienna Transplantation Center after four thousand renal transplantations

The Division of Transplantation at the Medical University of Vienna, Austria was established by Dr Franz Piza, who performed the first deceased donor kidney transplantation in Vienna in 1965. During the next 43 years, 4,849 transplants were performed at this unit. Data were analysed in the time period 1993-2006 for 2,165 deceased donor transplants (1,734 first and 431 regrafts) and 263 living donor transplants. Long-term follow-up was available for more than 95% of all grafts and all recipients had at least 9 months of follow-up. Two- and 6-year graft survival rates were 81.4% and 66.3%, respectively, for first deceased donor grafts, 76.1% and 61.8% for regrafts and 91.5% and 79.1% for living transplants. Appropriate immunosuppression, HLA matching and crossmatching supported by solid basic scientific research have proved successful in achieving good graft survival at our unit.

The Association Between Angiotensin Converting Enzyme Inhibitor or Angiotensin Receptor Blocker Use During Postischemic Acute Transplant Failure and Renal Allograft Survival

BACKGROUND

Postischemic acute renal transplant failure occurs in approximately one fourth of all dead donor transplantations. Uncertainty exists regarding the putative association between the use of angiotensin converting enzyme inhibitors (ACEIs) or angiotensin II AT1 receptor blockers (ARBs) and kidney transplant graft survival in patients with delayed allograft function.

METHODS

We conducted an open cohort study of all 436 patients who experienced an acute renal transplant failure out of all 2,031 subjects who received their first kidney transplant at the Medical University of Vienna between 1990 and 2003. Actual and functional graft survival was compared between users and nonusers of ACEI/ARB using exposure propensity score models and time-dependent Cox regression models.

RESULTS

Ten-year actual graft survival averaged 44% in the ACEI/ARB group, but only 32% in patients without ACEI/ARB (P=0.002). The hazard ratio of actual graft failure was 0.58 (95% confidence interval: 0.35-0.80, P=0.002) for ACEI/ARB users compared with nonconsumers. Seventy-one percent of subjects with ACEI/ARB had a functional graft at 10 years versus 64% of ACEI/ARB nonusers (P=0.027). The hazard ratio of functional graft loss was 0.48 (95% confidence interval: 0.24-0.91, P=0.025).

CONCLUSIONS

Use of ACEI/ARB in patients experiencing delayed allograft function was associated with longer actual and functional transplant survival.

International differences in dialysis mortality reflect background general population atherosclerotic cardiovascular mortality

Existing national, racial, and ethnic differences in dialysis patient mortality rates largely are unexplained. This study aimed to test the hypothesis that mortality rates related to atherosclerotic cardiovascular disease (ASCVD) in dialysis populations (DP) and in the background general populations (GP) are correlated. In a cross-sectional, multinational study, all-cause and ASCVD mortality rates were compared between GP and DP using the most recent data from the World Health Organization mortality database (67 countries; 1,571,852,000 population) and from national renal registries (26 countries; 623,900 population). Across GP of 67 countries (14,082,146 deaths), all-cause mortality rates (median 8.88 per 1000 population; range 1.93 to 15.40) were strongly related to ASCVD mortality rates (median 3.21; range 0.53 to 8.69), with Eastern European countries clustering in the upper and Southeast and East Asian countries in the lower rate ranges. Across DP (103,432 deaths), mortality rates from all causes (median 166.20; range 54.47 to 268.80) and from ASCVD (median 63.39 per 1000 population; range 21.52 to 162.40) were higher and strongly correlated. ASCVD mortality rates in DP and in the GP were significantly correlated; the relationship became even stronger after adjustment for age (R(2) = 0.56, P < 0.0001). A substantial portion of the variability in mortality rates that were observed across DP worldwide is attributable to the variability in background ASCVD mortality rates in the respective GP. Genetic and environmental factors may underlie these differences.

Long-term mortality and incidence of renal dialysis and transplantation in type 1 diabetes mellitus

AIMS

We investigated long-term mortality and requirement of renal replacement therapy (RRT) in type 1 diabetes mellitus (T1DM) to study risk factors and late complication incidence of T1DM in a prospective cohort study at Lainz Hospital, Vienna, Austria.

METHODS

In 1983-1984, T1DM patients [n = 648; 47% females, 53% males; age, 30 +/- 11 yr; T1DM duration, 15 +/- 9 yr; body mass index, 24 +/- 4 kg/m(2); glycated hemoglobin (HbA1c), 7.6 +/- 1.6%] were stratified into HbA1c quartiles [1st, 5.9 +/- 0.5% (range, 4.2-6.5%); 2nd, 6.9 +/- 0.3% (6.6-7.4%); 3rd, 7.9 +/- 0.3% (7.5-8.4%); and 4th, 9.6 +/- 1.3% (8.5-14.8%)]. Twenty years later, both endpoints (death and RRT) were investigated by record linkage with national registries.

RESULTS

At baseline, creatinine clearance, blood pressure, and body mass index were comparable among the HbA1c quartiles, whereas albuminuria was more frequent in the 4th quartile (+15%; P < 0.03). After the 20-yr follow-up, 13.0% of the patients had died [rate, 708 per 100,000 person-years (95% confidence interval, 557-859)], and 5.6% had received RRT [311 per 100,000 person-years (95% confidence interval, 210-412)]. Patients with the highest HbA1c values (4th quartile) had a higher mortality rate and a greater incidence of RRT (P < 0.04). In the Cox proportional hazards analysis, age, male gender, increased HbA1c, albuminuria, and reduced creatinine clearance were predictors of mortality (P < 0.05). Predictors of RRT were albuminuria (P < 0.001), reduced creatinine clearance (P < 0.001), and belonging to the 4th HbA1c quartile (P = 0.06). In Kaplan-Meier analysis, mortality was linearly associated with poor glycemia, whereas RRT incidence appeared to rise at a HbA1c threshold of approximately 8.5%.

CONCLUSION/INTERPRETATION

In the Lainz T1DM cohort, 13.0% mortality and 5.6% RRT were directly associated with and more frequently found in poor glycemia, showing that good glycemic control is essential for the longevity and quality of life in T1DM.

Confounding effect of comorbidity in survival studies in patients on renal replacement therapy

BACKGROUND

After taking other confounding factors into account, the impact of comorbidity on mortality was investigated when comparing mortality between five European countries, dialysis modalities and renal disease groups.

METHODS

The study included 15 571 incident patients on renal replacement therapy (RRT) from five national or regional registries participating in the European Renal Association-European Dialysis and Transplant Association Registry that collect comorbidity data. The presence of diabetes mellitus, ischaemic heart disease, peripheral vascular disease, cerebrovascular disease and malignancy was recorded at the start of RRT.

RESULTS

The comorbidities were each independently associated with mortality, with hazard ratios (HRs) ranging from 1.40 (95% CI: 1.30-1.51) for peripheral vascular disease to 1.65 (95% CI: 1.48-1.83) for diabetes. Age, gender, primary renal disease, modality and country together explained 14.4% of the variance in mortality; the comorbidities explained an additional 1.9%. In the comparison of renal vascular disease with glomerulonephritis, the crude HR of 2.40 (95% CI: 2.12-2.72) changed to 1.24 (95% CI: 1.09-1.41) after adjustment for age, gender, primary renal disease, treatment modality and country and to 1.06 (95% CI: 0.93-1.22) after further adjustment for the comorbidities. For the comparison between countries and other patient groups, the change in the survival estimate after adjustment for comorbidity was less.

CONCLUSION

Comorbidity is an important predictor for mortality. However, after adjustment for age, gender, primary renal disease, treatment modality and country, when comparing outcomes between patient groups the influence of comorbidity may be less important than expected.

A prospective study of anaemia and long-term outcomes in kidney transplant recipients

BACKGROUND

Anaemia is prevalent in kidney transplant recipients (KTR), and only few KTR with anaemia receive treatment with erythropoietin. Some have claimed that this undertreatment might contribute to suboptimal outcomes such as mortality and cardiovascular events in these patients. However, no evidence is currently available that anaemia is actually associated with such risks in KTR.

METHODS

We merged two cohorts of KTR to study the associations between anaemia and two outcomes: all-cause mortality and kidney allograft loss. Detailed information on the demographic and clinical characteristics of these 825 patients was available at baseline. As recommended by the American Society of Transplantation, anaemia was considered present if the haemoglobin concentration was < or =13 g/dl in men or < or =12 g/dl in women. Patients were followed using the Austrian Dialysis and Transplant Registry.

RESULTS

After 8.2 years of follow-up, 251 patients died and 401 allografts were lost. In multivariate analyses, anaemia was not associated with all-cause mortality (HR: 1.08; 95% CI: 0.80-1.45), but it was associated with 25% greater risk of allograft loss (HR = 1.25; 95% CI: 1.02-1.59). This association was even more pronounced in death-censored analyses. Analyses using haemoglobin as a continuous variable or in categories also found no association with mortality.

CONCLUSIONS

Anaemia may not be associated with mortality in KTR. In light of the recent findings of increased mortality in chronic kidney disease patients with higher haemoglobin treatment target, further evidence is needed to guide clinicians in the treatment of anaemia in these patients.

The Enigma of Hypertensive ESRD: Observations on Incidence and Trends in 18 European, Canadian, and Asian-Pacific Populations, 1998 to 2002

BACKGROUND

Despite improved treatment of hypertension and decreasing rates of stroke and coronary heart disease, the reported incidence of hypertensive end-stage renal disease (ESRD) increased during the 1990s. However, bias, particularly from variations in acceptance into ESRD treatment (ascertainment) and diagnosis (classification), has been a major source of error when comparing ESRD incidences or estimating trends.

METHODS

Age-standardized rates were calculated in persons aged 30 to 44, 45 to 64, and 65 to 74 years for 15 countries or regions (separately for the Europid and non-Europid populations of Canada, Australia, and New Zealand), and temporal trends were estimated by means of Poisson regression. For 10 countries or regions, population-based estimates of mean systolic blood pressures and prevalences of hypertension were extracted from published sources.

RESULTS

Hypertensive ESRD, comprising ESRD attributed to essential hypertension or renal artery occlusion, was least common in Finland, non-Aboriginal Australians, and non-Polynesian New Zealanders; intermediate in most European and Canadian populations; and most common in Aboriginal Australians and New Zealand Maori and Pacific Island people. Rates correlated with the incidence of all other nondiabetic ESRD, but not with diabetic ESRD or community rates of hypertension. Between 1998 and 2002, hypertensive ESRD did not increase in Northwestern Europe or non-Aboriginal Canadians, although it did so in Australia.

CONCLUSION

Despite the likelihood of classification bias, the probability remains of significant variation in incidence of hypertensive ESRD within the group of Europid populations. These between-population differences are not explained by community rates of hypertension or ascertainment bias.

[Peritoneal dialysis in patients with polycystic kidney disease]

In Austria, patients with end-stage renal disease caused by polycystic kidney disease are less frequently treated with peritoneal dialysis (PD) than patients with noncystic renal diseases (6% versus 8%). In contrast, the United States renal data system reports that more than one fifth of patients with polycystic kidney disease choose PD as their initial form of renal replacement therapy. The reasons for this difference are unknown. Extrarenal manifestations of the disease, such as diverticulosis, development of hernias or vascular aneurysms, may theoretically promote the occurrence of complications typically related to PD. However, studies undertaken to clarify these questions did not find any difference in the rates of peritonitis caused by diverticulosis or Gram-negative bacteria, and no differences were seen with respect to vascular complications. Nevertheless, in comparison with the general population, patients with polycystic kidney disease are more likely to develop hernias, and the incidence of herniation may be further increased by PD. In conclusion, patients with polycystic kidney disease who also have abdominal complaints such as meteorism and discomfort, or lumbago resulting from the markedly enlarged kidneys, should not be actively advised to have PD treatment. The same is true for patients with recurrent hernias. However, the technical survival, quality of dialysis, duration of therapy and rates of complications in PD are comparable in patients with cystic or noncystic kidney disease, and therefore all patients with polycystic kidney disease who do not have abdominal complaints or history of recurrent hernias should be informed that PD is an adequate form of renal replacement therapy, equally effective as hemodialysis.

Prognostic Associations Between Lipid Markers and Outcomes in Kidney Transplant Recipients

BACKGROUND

Hyperlipidemia is highly prevalent in kidney transplant recipients, but the prognostic significance for mortality and allograft survival in these patients has not been established sufficiently.

METHODS

We prospectively enrolled 733 kidney transplant recipients between 1996 and 1998. Clinical information was collected and blood was drawn for laboratory evaluation. Information on the previous transplantation procedures and organ donor were obtained from the Eurotransplant Foundation database. We used the Austrian Dialysis and Transplantation Registry for follow-up. Using multivariate proportional hazard regression, independent relations of fasting plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels to risk for death from any cause and risk for kidney allograft loss were examined.

RESULTS

During a median follow-up of 6.1 years, 154 patients died and 260 kidney allografts were lost. After careful multivariate adjustment, there were no significant associations between TG and TC levels and patient mortality. Patients in the highest quartile of TG and TC levels had no difference in risks for mortality compared with patients in the lowest quartile of these parameters (hazards ratio, 0.81; 95% confidence interval, 0.51 to 1.28; hazards ratio, 0.68; 95% confidence interval, 0.42 to 1.10, respectively). Similarly, no associations were found with allograft loss. Further analysis of associations between high-density lipoprotein cholesterol or low-density lipoprotein cholesterol categories and patient mortality or kidney allograft loss did not show associations.

CONCLUSION

Elevated levels of TC or its subfractions and elevated TG levels are not associated with increased risk for patient mortality or allograft loss in these kidney transplant recipients.

Angiotensin-converting enzyme inhibitor or angiotensin II type 1 receptor antagonist therapy is associated with prolonged patient and graft survival after renal transplantation

Angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II type 1 receptor blockers (ARB) reduce cardiovascular death in the general population, but data for renal transplant recipients remain elusive. Similarly, ACEI/ARB have been shown to reduce proteinuria, but data on graft survival are lacking. Therefore a retrospective open cohort study was conducted of 2031 patients who received their first renal allograft at the Medical University of Vienna between 1990 and 2003 and survived at least 3 mo. Patient and graft survival was compared between patients with versus without ACEI and/or ARB therapy. Data were analyzed with and without propensity score models for ACEI/ARB therapy. Medication and comorbidities were analyzed as time-dependent variables in the Cox regression analyses. Ten-year survival rates were 74% in the ACEI/ARB group but only 53% in the noACEI/ARB group (P<0.001). The hazard ratio (HR) of ACEI/ARB use for mortality was 0.57 (95% confidence interval [CI] 0.40 to 0.81) compared with nonuse. Ten-year actual graft survival rate was 59% in ACEI/ARB patients but only 41% in nonusers (P=0.002). The HR of actual graft failure for ACEI/ARB recipients was 0.55 (95% CI 0.43 to 0.70) compared with nonusers; the HR of functional graft survival was 0.56 (95% CI 0.40 to 0.78). Ten-year unadjusted functional graft survival rates were 76% among ACEI/ARB patients and 71% in noACEI/ARB recipients (P=0.57). In summary, the use of ACEI/ARB therapy was associated with longer patient and graft survival after renal transplantation. More frequent use of these medications may reduce the high incidence of death and renal allograft failure in these patients.

Long-term patient and graft survival in the eurotransplant senior program: a single-center experience

BACKGROUND

The Eurotransplant Senior Program (ESP) was launched in 1999, targeted to increase the supply of donor kidneys to the elderly. This program requires local allocation of kidneys from cadaveric donors >>65 years to recipients >>65 years.

METHODS

Of all patients >>65 years who received a kidney transplant in 1999-2002 at our center, 59 patients were transplanted through the ESP protocol (ESP group), and 44 patients received a transplant from a younger donor (EuroTransplant Kidney Allocation System, ETKAS group). Recipients were followed for up to 5.3 years using the Austrian Dialysis and Transplant Registry. Outcomes studied included all-cause mortality and allograft loss.

RESULTS

Age, sex, and comorbid conditions did not differ by group. Donor age was higher (69 vs. 36 years; P < 0.001) and cold ischemia time shorter in the ESP group (10 vs. 15 hr; P < 0.001). Number of HLA mismatches was greater in the ESP group (3.8 vs. 3.0; P = 0.003). ESP patients were more likely to receive induction therapy and less likely to receive cyclosporine A. Primary nonfunction, delayed graft function, operative mortality, rate of acute rejection episodes, and length of stay did not differ by group. Although serum creatinine at discharge was higher in ESP patients (1.7 vs. 1.4 mg/dL; P < 0.001), 4-year mortality (hazard ratio [HR] = 0.68; 95% CI: 0.31-1.49) and graft loss (HR = 0.61; 95% CI: 0.29-1.28) tended to be less.

CONCLUSIONS

Long-term patient and graft survival were comparable between elderly patients who received their organ via the ESP and the regular ETKAS algorithm.

Effects of single-nucleotide polymorphisms in MTHFR and MTRR on mortality and allograft loss in kidney transplant recipients

BACKGROUND

Plasma total homocysteine (tHcy) is associated with cardiovascular outcomes in kidney transplant recipients (KTR). The methylenetetrahydrofolate-reductase (MTHFR) 677C>T polymorphism, an important determinant of plasma tHcy concentrations, could therefore constitute an important prognostic marker.

METHODS

We prospectively followed 710 KTR over >6 years. The MTHFR677C>T, MTHFR1298A>C, MTHFR1793G>A, and MTRR66A>G polymorphisms were analyzed. Demographic, clinical, and transplant-related information was obtained, and patients were followed-up using the Austrian Dialysis and Transplant Registry. Using Cox regression, we established the independent relations of each genotype to the risk of death from any cause, and/or kidney allograft loss.

RESULTS

During a median follow-up of 6.1 years, 154 participants died and 260 kidney allografts were lost. Compared to patients with the MTHFR677CC genotype, patients with MTHFR677CT had an adjusted relative mortality risk of 1.02 (95%CI 0.70-1.47), and those with MTHFR677TT of 0.98 (95%CI 0.52-1.85). Compared to MTHFR677CC, the relative risks of kidney allograft loss were 0.93 (95%CI 0.70-1.23; MTHFR677CT) and 0.78 (95%CI 0.47-1.30; MTHFR677TT), respectively. None of the other genotypes were associated with the risks studied, either. These findings did not depend on whether we controlled for tHcy levels.

CONCLUSION

This study does not support the routine use of MTHFR or MTRR genotyping for prognostic evaluation or risk-stratification in kidney transplant recipients.

Proteinuria and hemoglobin levels in patients with primary glomerular disease

BACKGROUND

Anemia in association with nephrotic syndrome has been described in small patient series and case reports. Whether nephrotic patients develop anemia has not been formally investigated.

METHODS

We undertook a retrospective cross-sectional study of patients with biopsy-proven primary glomerular disease, various degrees of proteinuria, and creatinine levels less than 2 mg/dL (< 177 micromol/L). In addition to proteinuria, values for hemoglobin (Hb), age, body mass index (BMI), serum albumin and protein, and estimated glomerular filtration rate (eGFR) were derived from patient charts.

RESULTS

We studied 297 patients, 187 men and 110 women, aged between 16 and 81 years. Univariate analysis showed no correlation between Hb level and proteinuria in either sex. Stratification of women and men into quartiles according to proteinuria showed no differences in Hb levels among the 4 groups. Three of 52 non-nephrotic women (6%) were anemic (Hb < 12 g/dL [< 120 g/L]) compared with 11 of 58 nephrotic women (19%; P = 0.047). Multiple regression analysis of all patients showed Hb level to have a correlation with sex (P < 0.001), BMI (P < 0.001), and eGFR (P = 0.005); negative correlation with age (P = 0.028); and borderline negative correlation with proteinuria (P = 0.054). In women, BMI showed a positive correlation with Hb level (P = 0.030). Proteinuria did not reach statistical significance (P = 0.093). In men, BMI (P = 0.001) and eGFR (P = 0.013) were associated positively and age (P = 0.031) was associated negatively with Hb level.

CONCLUSION

These results indicate that nephrotic syndrome is not associated with anemia in men, but with a tendency to decrease Hb levels in women.

Prevalence of co-morbidity in different European RRT populations and its effect on access to renal transplantation

BACKGROUND

This study compared the prevalence of co-morbidity in patients starting renal replacement therapy (RRT) between European countries and further examined how co-morbidity affects access to transplantation.

METHODS

In this ERA-EDTA registry special study, 17907 patients from Austria, Catalonia (Spain), Lombardy (Italy), Norway, and the UK (England/Wales) were included (1994-2001). Co-morbidity was recorded at the start of RRT.

RESULTS

The prevalence of co-morbidity was: diabetes mellitus (DM) (primary renal disease and co-morbidity) 28%, ischaemic heart disease (IHD) 23%, peripheral vascular disease (PVD) 24%, cerebrovascular disease (CVD) 14% and malignancy 11%. With exception of malignancy, the prevalence of co-morbidity was highest in Austria, but differences were small among other countries. With exception of DM, males suffered more often from co-morbidity than females. In general, the percentage of haemodialysis was higher in patients with co-morbidity, but treatment modality differed substantially between countries. Using a Cox regression with adjustment for demographics, country, year of start and other co-morbidities, the presence of each of the co-morbid conditions made it less likely [RR; 95%CI] to receive a transplant within 4 years: DM [0.79; 0.70-0.88], IHD [0.59; 0.50-0.70], PVD [0.57; 0.49-0.67], CVD [0.49; 0.39-0.61], and malignancy [0.32; 0.24-0.42]. The age, gender and year of start adjusted relative risk [95%CI] to receive a renal transplant within 4 years ranged from 0.23 [0.19-0.27] for Lombardy (Italy) to 3.86 [3.36-4.45] for Norway (Austria = reference). These international differences existed for patients with and without co-morbidity.

CONCLUSIONS

The prevalence of co-morbidity was highest in Austria but differences were small among other countries. The access to a renal graft was most affected by the presence of malignancy and least affected by the presence of DM. International differences in access to transplantation were only partly due to co-morbid variability.

Prevalence of LADA and frequency of GAD antibodies in diabetic patients with end-stage renal disease and dialysis treatment in Austria

BACKGROUND

The prevalence of individuals with latent autoimmune diabetes in adults (LADA) among diabetic patients with end-stage renal disease is unknown. Furthermore, there are no references in the literature about the persistence of glutamic acid decarboxylase antibodies (GADA) in uraemic LADA patients. The aim of the study, therefore, was to evaluate the prevalence of LADA, classified according to special features, in diabetic patients undergoing dialysis therapy as well as to find out the frequency of GADA in these patients. In addition, we investigated vascular risk factors and the prevalence of vascular diseases in each type of diabetes.

METHODS

538 patients undergoing chronic dialysis therapy from 37 Austrian dialysis centres were analysed in the study. Patients were divided into three groups: patients with type 1 or type 2 diabetes and patients with LADA. The classification of the different types of diabetes was based on the guidelines of the German Diabetes Society. We measured GADA and estimated the baseline data with reference to body mass index (BMI), age at onset of diabetes and at initiating dialysis therapy, the actual values of haemoglobin (Hb) A1c and cholesterol and the prevalence of vascular diseases by using a structured questionnaire.

RESULTS

Type 1 diabetes was classified in 52 patients, type 2 diabetes in 434 and LADA in 52 (9.7%). The prevalence of positive GADA was 17.3% in the type 1 diabetic patients and 26.9% in the LADA patients. There was no positive GADA in the type 2 diabetic subjects. Age at the onset of diabetes and age at the start of dialysis were approximately the same in the LADA and the type 2 diabetic patients, while the age of the subjects with type 1 diabetes was significantly lower (P<0.001). BMI was significantly lower (25+/-3 vs 27+/-5 kg/m2) in the LADA patients than in the type 2 diabetic patients. The mean HbA1c value in the LADA patients was significantly higher than in the subjects with type 2 diabetes (P<0.01). Blood pressure (BP) was similar between LADA and type 1 or type 2 diabetes, though diastolic BP tended to be lower in the LADA patients than in the type 1 diabetics. The cholesterol levels were comparably high in each type of diabetes. In the LADA patients, the prevalence of retinopathy was lower than in the type 1 diabetics and the prevalence of stroke and angina pectoris was lower than in the type 2 diabetic patients, but the differences were not significant.

CONCLUSIONS

The prevalence of LADA in diabetic patients on maintenance dialysis was 9.7%. This value is comparable to the frequency of LADA at onset of diabetes. The frequency of persisting GAD autoantibodies was 27% in the LADA patients and 17% in the type 1 diabetic patients. BMI was significantly lower in the LADA patients than in the type 2 diabetic patients, while diastolic BP only tended to be lower in the LADA patients than in the type 1 diabetics. The prevalence of vascular diseases was not significantly different between LADA and types 1 or 2 diabetes. According to our data it can be assumed that only a few uraemic patients with LADA are suitable for simultaneous pancreas-kidney transplantation.